Although neural systems thought to underlie social bonding and the social regulation of emotion are increasingly well documented in animals and nonhuman primates, the candidate neural mechanisms responsible for these effects in humans remain speculative. Moreover, very little work to date has sought specifically to identify how social affiliation and emotion circuits function in a context that combines social interaction with externally generated emotional stress. In the proposed study, we plan to closely examine human social contact, attachment, and the social regulation of emotion, in vivo, using functional magnetic resonance imaging (fMRI). We will monitor functional brain activity related to physical social contact, physical contact from a familiar other, and the social regulation of both threat responding and empathy, across four conceptually linked studies utilizing 124 participants drawn from a larger (n = 172) normative sample of young adults (ages 24 to 28) whose social behaviors, parental and peer social experiences, and personality characteristics have been assessed annually from the ages of 13-22. This proposal will greatly expand our knowledge of how social bonding, familiarity, and soothing are instantiated neurally, as well as how social contact and soothing regulate neural systems supporting emotional responding. Moreover, the proposed design will allow us to evaluate the moderating influences on these neural systems of relationship characteristics such as status, quality and closeness; individual characteristics such as broad dimensions of emotion-regulatory personality, attachment and overt social behavior; and historical factors such as levels of parental affection versus abuse and neglect, and levels of adolescent peer integration versus rejection. A deeper understanding of the neural circuitry underlying social behavior and the social regulation of emotional responding promises not only to contribute to basic progress in neuroscience, biomedical research, social science, public health, and epidemiology, but also to our understanding of, and efficacy in treating, a number of severely debilitating affective and neurodevelopmental disorders such as Autism, Fragile X, William's Syndrome, Schizophrenia and even Major Depression.